Mercury’s speed also apparently made the name apt for English speakers wishing to describe those whose moods travel quickly between extremes, a meaning mercurial has had since the …

medical specialized containing or caused by mercury: mercurial drugs (Definition of mercurial from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

MERCURIAL definition: changeable; volatile; fickle; flighty; erratic. See examples of mercurial used in a sentence.

If you describe someone as mercurial, you mean that they frequently change their mind or mood without warning.

There are 13 meanings listed in OED's entry for the word mercurial, four of which are labelled obsolete. See ‘Meaning & use’ for definitions, usage, and quotation evidence.

Definition of mercurial adjective in Oxford Advanced American Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Dec 19, 2025 · If it proceed from the mercurial, there will generally be some tenderness of the gums, a soft and flabby state of the sides of the tongue, and it will generally be more obstinate.

MERCURIAL meaning: 1 : changing moods quickly and often used to describe someone who often changes from being happy to being angry or upset in a quick and unexpected way; 2 : …

Mercurial describes someone whose mood or behavior is changeable and unpredictable, or someone who is clever, lively, and quick. With a mercurial teacher, you never know where you …

1. changeable; fickle; flighty; erratic: a mercurial nature. 2. animated; lively; sprightly. 3. pertaining to, containing, or caused by the metal mercury. 4. (cap.) of or pertaining to the god Mercury.